6-arylamino-2-hydroxy-naphthalenes and process of making same



Patented May 2, 1933 UNETEE aaraar easier;

WERNER ZERWECK AND WILHELM HECHTENBERG, F FRANKFORT-ON-THE-MAIN- FECHENHEIM, GERMANY, ASSIGNORS TO GENERAL ANILINE WORKS, INC., OF NEW YORK, N. Y., A CORPORATION OF DELAWARE G-ARYLAMINO-2-HYDROXYNAPHTHALENES AND PROCESS OF MAKING SAME No Drawing. Application. filed June 2'7, 1930, Serial No. 464,432, and in Germany July 24, 1929.

Our present invention relates to 6-arylamino-2-hydroxy-naphthalenes and to a process of making same.

I These new compounds are valuable interb mediates for the production of dyestuffs.

They correspond to the general formula:

The process of manufacturing these compounds in accordance With this invention comprises heating 6-arylamino-naphthalene- 2-sulfonic acids With molten caustic alkali. This operation may be carried out also at raised pressure.

The smooth course of this reaction, in

spite of the high temperature necessary for 2 splitting off the fl-sulfonic group, is the more surprising since 6-amino-naphthalene-2-sulfonic acid does not yield 6-amino-2-naphthol in the presence of molten alkali and arylamino groups are known to be more easily attacked by molten alkali than amino groups.

In order to further illustrate our invention the following examples are given, the parts being by Weight and all temperatures in Centigrade degrees, but We Wish it however, to be understood that We are not limited to the particular products nor reaction conditions mentioned therein Example 1 10 parts of 6-phenylamino-naphthalene-2- sulfonic acid (described in Journal f. prakt. Chemie (2) vol. 71, page 447) are introduced at about 280 into a molten mixture of 60 parts of caustic potash and 6 parts of Water. Then the temperature is raised to 300 and maintained there for a short time. When cool the mass is dissolved in Water and the formed G-phenylamino-2-hydroXy-naphthalene precipitated by means of sulfuric acid.

F or purification it may be redissolved in caustic soda solution and bisulfite or recrystallized from mono-chloro-benzene. It cor responds to the formula:

is easily soluble in dilute caustic alkali solutions and melts at 134.

Example 2 124 parts of 6-para-tolylamino-naphthalenc-2-sulfonic acid (prepared according to 0:

droXy-naphthalene thus obtained corresponds to the formula:

HaC-NH It represents, When recrystallized from mono-chloro-benzene, colorless crystals meltlng at 144.

E sample 3 198 parts of 6-phenylamino-naphthalene- 2-sulfonic acid (of strength) are introduced into a molten mass of 375 parts of caustic potash and parts of Water. 35 Then the Whole is heated in an autoclave to 265270 for 3 4 hours. lVhen cool the mass is dissolved in about 4000 parts of Water. From the filtered solution G-phenylamino 2- hydroxy naphthalene is precipitated by the addition of 435 parts of sulfuric acid of 66f B. The precipitate is filtered off, washed with water till neutral and dried. The product thus obtained in a good yield and purity is identical with the product of Example 1.

Example 4 28 parts of '6-phenylamino-naphthalene-2- sulfonic acid, 40 parts of caustic soda and 13 parts of water are heated together in an autoclave provided with a stirrer to 255260 for about 5 hours. The mass is worked up according to Example 1. The product is identical to that of Example 1.

E wample 5 Gamma It melts at 168170 and is nearly insoluble in a dilute caustic soda solution.

e claim 1. Process which comprises heating a 6- arylamino-naphthalene-Q-sulfonic acid of the general formula:

(VVherein R means an aryl radical of the henzene or naphthalene series) with molten caustic alkali.

2. Process which comprises heating 6- phcnylamino-naphthalene-2-sulfonic acid of the formula:

SOaH Q with a molten caustic alkali.

3. As new compounds the 6-arylamino-2- hydroXy-naphthalenes of the general formula:

(lVherein R means an aryl radical of the benzene or naphthalene series) which compounds are colorless crystallized substances having a definite melting point.

4. As a new compound the fi-phenylamino- 2-hydroxy-naphthalene of the formula:

which compound is a colorless crystallized substance, melting when recrystallized from mono-chloro-benzene at 134, easily soluble in a caustic alkali solution.

Process which comprises heating 6-paratolylamino-naphthalene-2-sulfonic acid of the formula:

I SOaH with a molten caustic alkali.

6. Process which comprises heating 6-,8- naphthylamino-naphthalene-2-sulfonic acid of the formula:

with a molten caustic alkali.

7. As a new compound the 6-para-tolylamino-Q-hydroxy-naphthaleue of the formula:

which compound is a colorless crystallized substance melting when recrystallized from mono-chloro-benzene at 144 C.

8. As a new compound the G-B-naphthylamino-Q-hydroxy-naphthalene of the for which compound melts at 168 to 170 C. and is nearly insoluble in a dilute caustic soda solution.

In testimony whereof, we afiix our signatures.

\VERNER ZERXVECK. WILHELM HECHTENBERG. 

